Insulator.



G. FACCIOLI.

msumon.

APPLICATION FILED SEPT- 25- 1914. 1, 1 60,702. Patented Nov. 16, 1915.

Witnesses I Inventor:

' H is a corneg.

UNITED STATES PATENT OFFICE,

GIUSEPPE FACCIOLI, or PITTSFIELD, MASSACHUSETTS, assmnon'v'ro GENERAL nnncrmc COMPANY, A conronarxon or NEW YORK.

INSULATOR.

Application filed September 25, 1914. Serial No. 863,430.

To all whom it may concern:

Be it known that I, GIUSEPPE FACcIoLI, a citizen of the United States, residing at Pittsfield, county of Berkshire, State of Massachusetts, have invented certain new and useful Improvements in Insulators, of which the following is a specification.

My invention relates to insulators containing liquid dielectric or insulating mater al, such as oil, and more particularly to the 1nsulation of conductors where they pass through conductive walls of tanks or casings which themselves contain such fluid insulating material.

My aim is to overcome the leakageto which insulators of this oil-filled type are commonly subject, and also to improve their general serviceability and simplify and cheapen their construction.

The invention is especially applicable to the leads of oil-filled transformers operating with currents of very high voltages, such as 50,000 to 2,000,000 volts, for example,and

1n explaining it and describing the best embodiment at present known to me I have hereinafter referred especially to this use. However, while my invention extends to various specific features anddetails and combinations and arrangements of partsherein illustrated and set forth, it is not confined thereto, but can be otherwise carried on and embodied.

An oil-filled transformer lead using the term lead in its common extended sense as including the conductor and all of the insulating and other structure associated with it, generally consists of a number of parts joined and secured together with a view to making the lead as nearly oil-tight as possible. Such leads are mounted on the upper wall or cover of the transformer. casing or tank and often extend down into the oil inside of it; but whether they extend down into the oil or not, they usually have one or more joints (both within and without the casing) leakage at any of which will result in a more or less gradual emptying of the lead and in a consequent reduction of its insulating effectiveness. In spite of the utmost care in design and workmanship, at least one of these joints inany lead will usually-v fail of being quite oil-tight, and the oil thus leaking out is often annoying in itself, irrespectiveof the danger due to the emptying of the lead.

1 the transformer tank and is open at its lower Patented Nov. 16,1915.

end so that the oil has free access to its in terior. With this arrangement, once the lead is filled the atmospheric or other pressure on the oil in the tank will keep it full, so that the only leakage that can be of anyconsequence is leakage of air into the leadjat the omt between the hollow insulator and the conductor, or at any joints in'the insulat'or itself; Joints of this sort can be made air-tlghtvmore easily than many of those in leads of other types could be made oil-tight.

The accompanying drawing shows somewhat diagrammatically alead constructed in accordance with my invention and mounted in thegupper wall'cover of the tankor casing of. a-tra'nsformer' or an oil switch,

certain offlthe parts being-partly broken aWayand in section in order that theinternal construction may be visible.

The hollow insulator 1 around the conductor 2 is shown asa single piece having a circumferentially corrugated upper portion of conoidal form and a plain cylindrical lower portion,'though it will be understood that it need not necessarily be in one pie e and that its particular form is immaterial as regards my invention. cover 30f the transformer tank hasan opening through which the cylindrical portion of p the insulator 1 extends down below the level 4 of the oil in the tank, and in this opening is mounted a metal casing 5 that in effect forms an extension of the upper tank wall 3 downward around the conductor 2 and the insulator 1 below the levellof the oil.' As shown, this metal casing 5 has at its upper end an external flange 6 that rests on the The upper wall ,or,

cover and-is secured thereto by any suitable I means, and at its lower edge an internal flange 7 that forms a seat for supporting the msu shown as having an upwardly extending inner wall 8 that serves to insure that the greatest; concentration of the'electrical Stress between the tank wall and theconductor 2 ator ,1. .The metal casing 5-is also shall be in the oil and not in the air around the lead, and is of ample width lengthwise of the conductor to avoid excessive concentration even in the oil. As shown, the insulator 1 sits in the double walled casing 5 out of contact with either the outside or the inside wall, and there are openings 9 through the flange 7 that give the oil in the tank free access to .the annular space between the insulator and the inner wall 8.

If desired, any suitable means may be employed to make the joint between the flange 6 and the cover 3 air or oil tight, and also that between the flange 7 and the lower edge of the insulator 1; but this is not really necessary unless the pressure in the tank is to be higher than atmospheric: on the contrary, either or both of these joints may without harm be so loose that the tank is practically open to the'atmosphere. For holding the lower end of the conductor 2 in its proper central position with reference to the surrounding parts and for insuring against passage of current between'said conductor and any other electrical part that might otherwise come too near it I may employ insulating means 10 arranged around said conductor 2 below the casing 5. This supplemental insulator 10 is shown as of an ordinary circumferentially corrugated frusto-conical form, and it is supported and secured by means including a cap piece 11 and a nut 12 threaded on the conductor 2,

a washer or gasket 13 being interposed between them. The oil in the tank has access to the interior of the insulator 10 and to the open lower end of the insulator 1 through openings 1-1 in the cap piece 11. The conductor 2'is supported and in part maintained in proper central position in the insulator 1 by any suitable means 15 adapted to make an absolutely air-tightjoint between it and the upper end of the insulator, the particular means shown including parts similar to the parts 11, 12 and 13 associated with the insulator 10.

While a lead constructed as shown and described may be initially put in place and filled with oil in various ways, a good method is to turn it bottom end up,.introduce the oil through the openings 14 in the cap piece 11, temporarily close these openings to prevent the escape of oil through them, turn the lead end for end and insert it in its opening in the tank cover 3 until the flange 6 of its casing 5 rests thereon as shown, and then unseal the openings 14. Assuming that the pressure in the tank is atmospheric, if oil can leak out between the upper surface of the flange 7 and the lower edge of the insulator 1, it will merely accumulate in the annular space between the insulator and the outer wall of the casing 5 till it is even with the oil level in the tank, after which nofurther leakage will occur. All the oil esof parts or sections cemented or otherwise 7 firmly and tightly secured together.

A shield 16 of downwardly convex form is secured at the bottom of the lead, this shield being intended to prevent bubbles of air or vapor forming in the oil in the tank 4 or case from entering the lead and accumulating at its upper end. This shield is mounted on the conductor 2 beneath the nut 12 and is held in place by a nut 17. It may be of either metal or insulatingmaterial, depending on the clearances and other conditions inside of the casing 3.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The combination with an oil-filled tank of a hollow oil-filled insulator for the passage of a conductor thereinto extending through its upper wall down below the level of the oil, said insulator being open at its lower end so that the oil in the tank has access to its interior.

2. The combination with an oil-filled tank and a conductor extending through its upper wall of a metal'casing forming an extension of the tank wall downward around the conductor below the level of the oil in the tank and an oil-filled insulator around the conductor extending down within said casing below the level of the oil in the tank, said insulator being open at its lower end so that the oil in the tank has access to its interior.

3. The combination with an oil-filled tank and a conductor extending through an opening-its upper wall of a double walled metal casing secured in said opening and extending downward around the conductor below the level of the oil in the tank and an oilfilled insulator around the conductor extending between the walls of said casing out of contact with the inner one down below the level of the oil in the tank, said insulator being open at its lower end so that the oil in the tank has access to its interior and the space between said insulator and the ing and extending downward within it below the level of the oil in the tank, and insulating means around said conductor below said casing for keeping the conductor in place with reference to said casing.

The combination with an oil-filled tank open to the atmosphere of an air-tight hollow oil-filled insulator for the passage of a conductor into said tank extending through 10 its upper wall downbelow the level of the oil, said insulator being open at the lower end so that the oil in the tank has access to its interior.

In Witness whereof, I have hereunto set my hand this 21st day of Sept, 19H.

GIUSEPPE FACCIOLI.

W. W. LEWIS. 

